Zeta form of quinacridone

ABSTRACT

A red pigment comprises linear quinacridone in the zeta crystal phase characterized by an X-ray diffraction pattern exhibiting six strong lines corresponding to interplanar spacings of 14.06A, 6.38A, 3.45A, 3.35A, 3.11A, and 2.11A; and six weak lines with interplanar spacings of 7.05A, 4.35A, 3.91A, 3.59A, 3.18A, and 2.83A.

Tyson et a1. July 1, 1975 [54] ZETA FORM OF QUINACRIDONE 3,726,8734/1973 Hashizume et al 260/279 R [75] Inventors: Ronald S. Tyson,Piscataway; FOREIGN PATENTS OR APPLICATIONS Leonard Shap ro, East Brunsic 1,043,677 9/1966 United Kingdom 260/279 R both of NJ. 7

[73] Assignee: Sun Chemical Corporation, New Primary Exl1ml'nerD0nald G-Da S York, Assistant ExaminerMary C. Vaughn Attorney, Agent, orFirm-Cynthia Berlow [22] Flledz Aug. 20, 1973 [21] Appl. No.: 389,986[57] ABSTRACT A red pigment comprises linear quinacridone in the [52]U.S Cl 260/279 R; 8/1 D; 106/288 Q zeta crystal phase characterized byan X-ray diffrac- [51] Int. Cl. C07d 37/22; C07d 37/18 on Pa tern xhibting SiX Strong lines corresponding [58} Field of Search 260/279 R o nrpl n r p i g Of 1 A, 4 A.

335A, 3.11A, and 2.11A; and six weak lines with in- [56] References Citd terplanar spacings of 7.05A, 4.35A, 3.91A, 3.59A,

UNITED STATES PATENTS 318A and 3,256,285 6/1966 Fuchs et a1 260/279 R 1Claim, N0 Drawings 1 ZETA FORM OF QUINACRIDONE This invention relates toimproved quinacridone pigments. More specifically it relates to a newcrystalline form of quinacridone and to a process for producing it It isknown that linear trans quinacridone which is 5 represented by thestructural formula 0 i H @i ergp i i1 i v 1 can be produced as pigmentsin avariety .of crystal forms which exhibit different X-ray diffractionpatterns. Examples of these include 1. alpha phase. defined in U.S. Pat.N.o.-2,8 44.484 as characterized by three strong lines with interplanarspacings of 1424A. 3.46A..and 3.19A; two lines of moderate intensitywith interplanar spacings-of 6.32A

and 7.13A', two weak lines with interplanar spacings of 5.30A and 4.27A.This is stated to be a bluish red pigment of excellent strength andintensity.- I

11. betaphase', defined in U.S. Pat. No. 2.844.485 as characterized bytwo strong lines at interplanarspacings of 15.23A and 3.3 1A and threelines of lesser intensity at interplanar spacings of 7.55A, 5.47A. and4.06A. This is a stated to be a violet pigment of excellent intensityand strength.

lll. gamma phase. defined in U.S. Pat. No. 2.844.581

as characterized by three strong lines at interplanar spacings of 1358A.6.41A. and 3.37A and four relatively weak lines at interplanar spacingsof 6.70A. 524A. 4.33A. and 3.74A. This is stated to be a bluish redpigment of excellent strength and intensity.

1V. delta phase. defined in U.S. Pat. No. 3.272.821

as characterized by three strong lines at interplanar spacings of 13.6A.6.75A. and 6.41A; three moderate lines at interplanar spacings of 6.63A.3.37A. and 3.34A; and weak lines at 523A. 4.36A. 4.11A. 3.74A.

3.55A. 3.18A. 3.12A. 2.95A. and 2.8lA. This is stated 4 mentaryp'ropertiesThis process. known as condition- 1 ing', is generallycarried out by grinding or milling. usually in the presence of' asolvent. U.S. Pat. No. 2.844.484. for example. discloses the dry millingof linear quinacrido'nes with an inorganic salt such as sodium chloride;U.S. Pat. No.12.844.485 discloses milling with an inorganic salt in thepresence of an aromatic hydrocarbonor halogenated aromatic hydrocarbonliquid:

uis. Pat/No". 2.844.581 discloses salt milling with dimethyl formamide;U.S. Pat. No. 3.272.821 discloses subliming the crude product in avacuum of ().()5().1 mm. Hg at a temperature of .4O 5 *48OC.;

It has now been f oundthat there exists a further crystal modificationof quinacridone which will be referred to in the followingas 'zetzuphasequinacridone which differs from the known crystallin'e'forms ofquinacridone and its derivatives both in shade and in purity of color. 7

The zeta phase ofquinacridone is characterized by strong lines at 1406A.6.38. 1. 3.45A. 3 .35A. 3.11A. and 2.'11A and weakglines at7.05A..4.35A. 3.9m. 3 59A 3.18A, and 2.83A..ln hue this product is abrilliant red pigment of excellent strength and intensity. In

properties this product demonstrates the resistanceto light. acids.alkalies. and solvents which characterizes the previously known crystalvarieties of linear trans qui nac r idones. I I v I In accordance withthe practice of this invention. the crude linear quinacridone isconditioned by adding the presscake to an organic or inorganic liquid orwatersoluble solid having at least one hydroxyl group. such as forexample ethanol. glycerine. ethylene glycol. diethylene glycol. phenol.o-cresol. o-chlorophenol. boric acid. phosphoric acid. sulfuric acid.oxalic acid. formic acid. acetic acid. citric acid. toluene sulfonicacid. xylene sulfonic acid. and the like. and mixtures thereof. Theamount of the conditioning agent employed varies with the agentselected.

The resulting slurry is refluxed for about 2 to o. and preferably about4. hours: filtered; and washed with water. If desired. the resultingpigment may be dried at about 60 to 90. and preferably at about C.

The new zeta-phase quinacridone gives an X-ray diffraction pattern whichshows that the crystal structure is entirely different from those of theknown quinacridone pigments. While this new crystalline form shows someX-ray spacings similar to the known forms. there are many intense andweak lines that do not correspond to those of the known alpha. beta-.gamma-. deltaand epsilon-forms of quinacridone. as shown in thefollowment of brilliant yellowish shade. ing table:

Zeta-phase Ouinacridone Pigment a ,13 y A e 7.()5w 7.13m 7.55m 6.70m/w0.75s (1.76m 6.66m

6.38s 6.32m 6.415 6.415 6.47s

4.35w 4.27w 4.06m 4.33m/w 436w 5.25w

3.59w 3.55w 3.52w

3.45s 3.46s 3.38s

118W 3.19s 3.18w

5: strong. m= moderate. w= weak The method of preparing the crudequinadridone is not critical. In general. however, it is convenient toprepare it by the ring closure in polyphosphoric. acid of 2.S-dianilinoterephthalic acid or ester thereof and striking the resultingsolution into water. as described in US. Pat. Nos. 3.257.405. and3.342.823.

Compared to other quinacridone crystalline types of similar shade. theproduct of this invention is stronger. cleaner. and more convenient andeconomical to produce. The present process eliminates the need for-EXAMPLE I A 100 Parts of polyphosphoric acid l as H -,PO.) werethoroughly mixed with parts of 2.5- dianilinoterephthalic acid; themixture was heated with agitation to 85C. for about 24 hours. Thereaction mixture was then cooled; when the temperature was below 65C..l0 parts of water were added gradually with stirring; the mass was thendrowned into an additional 700 parts of water. precipitating a crudequinacridone.

B. I00 Parts of the crude presscake of part (A) were added to about 44parts of sulfuric acid to adjust the acid concentration to 35 per cent.exclusive of the pigment. The resulting slurry was refluxed for 4 hours,filtered. and washed with water. 12 Parts of red quinacridone wereobtained.

The linear quinacridone product was crystalline and exhibited thetypical X-ray diffraction pattern of the zeta phase.

It is entirely different from the forms of quinacridone that have beendescribed previously. Because of its high strength and cleanliness. thisnew form is a superior red pigment particularly suited for use inprinting inks. paints. plastics. and textiles.

EXAMPLE 2 the zeta crystal phase characterized by an X-ray dif-'fraction pattern exhibiting six strong lines corresponding tointerplanar spacings of 14.06-A. 6.38A. 3.45A. 3.35A. 3.] IA. and 2.] 1Aand six weak lines with interplanar spacings of 7.05A. 435A. 3.9lA,3.59A; 3. l 8A.

and 2.83A.

1. A RED PIGMENT CONSISTING OF LINEAR QUINACRIDONE IN THE ZETA CRYSTALPHASE CHARACTERIZED BY AN X-RAY DIFFRACTION PATTERN EXHIBITING SIXSTRONG LINES CORRESPONDING TO INTERPLANAR SPACING OF 14.06A, 6.38A,3.45A, 3.11A 3.35A, 3-11A, AND 2-11A AND SIX WEAK LINES WITH INTERPLANARSPACINGS OF 7.05A, 4.35A, 3.91A. 3.59A, 3.18A AND 2,83A.